Hypertension is a major risk factor for cardiovascular disease affecting about 30% of the population in the United States and its prevalence in expected to rise. One of the main reasons for the failure to treat this disease is the lack of understanding of the mechanisms. The role played by the carotid sinus in maintaining blood pressure has recently been under intense investigation. A widely accepted hypothesis that its activity is increased in hypertension remains untested due to the lack of a technology for recordings in very small nerves. The central hypothesis of this proposal is that the time course of the development of hypertension can be studied with a novel stable nanowire interface with the carotid sinus nerve (CSN) in a chronic spontaneously hypertensive (SH) rat preparation. The mechanical properties of the interface will be optimized by matching the mechanical properties of the implant to that of the nerve. The biocompatibility of the interface will be enhanced by adsorbing collagen onto the surface of the insulation to match the endoneurium environment. The wire will be implanted in SH rat chronic preparation for periods of three months and the hypothesis will be tested with two specific aims: The first aim is to develop a nanowire interface to record activity in the carotid sinus nerve. The second aim is to test the hypothesis that the CSN activity is indeed increasing and that its time either precedes the development of hypertension or is simultaneous with it. The relevance of the proposal is that it provides a novel method to monitor the activity of such a small nerve and to relate its activity to the development of one of the most pervasive disease, hypertension. In addition, this technique is applicable to other parts of the autonomic nervous system such as the vagus nerve in order to monitor and restore the function of internal organs.